1 Clement casually refers to the dead as Asleep just like the New Testament. Polycarp’s Epistle to the Philippians makes no reference to any After Life, only the promise of Resurrection, same with the Rule of Faith and Old Roman Symbol.
Justin Martyr in Dialogue with Trypho 80:9 says that those who teach you to go to Heaven when you Die and deny the Bodily Resurrection are not Christians. Defenders of the Intermediate State insist the point of this is only the later and the former is only wrong when it’s paired with the later. But to me the point is that they innately go together.
There are two Justin Quotes they then cite as in support of the Intermediate State, both are also from Dialogue with Trypho, one in chapter 5 and the other in chapter 6. In both cases it is the other person not Justin himself talking, but still someone who is almost right just getting his Soul/Spirit distinction terminology off. The Spirit Returns to God when the Body dies, but the Soul or Psyche in Greek is where Conciseness lies and is only awake when Body and Spirit are united.
I think chapter 5 is using the word “place” in an abstract sense. The righteous may be sleeping soundly then the unrighteous but both are still asleep. The title of chapter 5 is “the Soul is not in itself immortal”.
What Justin says in response critiques the Platonism of their perspective.
Then chapter 18 and 20 of the First Apology are quoted. Chapter 18 is about him reminding the Pagans and Philosophers reading what they already believe. And in Chapter 20 all he conceded Christian belief to have in common with that is the word “sensation”. In neither of these is explaining the Christian view of the Afterlife the objective Again my view is that the Soul is Asleep not Dead.
Tatian who was influenced by Justin but also became heavily Platonized still held to the Soul not being Immortal. In Address to the Greek Chapter XIII even the Souls of believers are Dissolved until the Resurrection.
Athenogaras in On The Resurrection Chapter XVI lays out a Soul Sleep view quite clearly.
Now I’ve seen Athenogaros quoted in support of Soul Sleep using A Plea for The Christians chapter 31. On The Resurrection is what he wrote specifically to clarify what he saw as the Christians on these issues, this apology written to a Pagan Audience naturally runs a greater risk of being misunderstood.
Yet still he speaks only of living a better life after this one, and calls it Heavenly not located in Heaven. He says we will be near God because that’s what New Jerusalem will be.
Marcu Minucius Felix in a dialogue titled Octavius Chapter XXXIV presents Soul Sleep as the presumed common opinion of all Christians.
The first version of an intermediate state to emerge among Christians wasn’t about anyone going to “Heaven” but about Abraham’s Bosom being part of or right next to Hades deep inside the Earth. This is the more logical conclusion to draw about Abraham’s Bosom when you take the Luke 16 Parable literally.
We see this in Irenaeus Against Heresies 5.31.2 and the Discourse to the Greek Concerning Hades often attributed to Hippolytus. Tertullian mostly followed them but had only the Martyrs go right to Heaven when they died. Even Origen, the first real enemy of Soul Sleep, had to admit that Biblically Paradise is located within the Universe not outside of it, even Garden being moved to the ‘Third Heaven” traditions would have still originally mean within the Universe, Heaven just meant the Sky and Outer Space to the Ancients.
The people who kept believing in Soul Sleep while the Greek and Latin Churches started moving away from it were various Semitic Christians. It was Arab Christians Origen went after. And then Aramaic Christians continued to teach Soul Sleep into the 4th and 5th Centuries like Apharat, Ephrem and Narsai.